1. Field of the Invention
The present invention relates to a measurement unit of a battery voltage; in particular, to a battery voltage measurement system with self-calibration capability.
2. Description of Related Art
Presently, the transportations use fossil fuels as a major power source. However, burning the fossil fuels may cause ecological environment problems and greenhouse effects. For reducing the dependency on fossil fuels, every country of the world is developing alternative energy for replacing fossil fuel. Because the electric car may be environmentally-friendly, many major vehicle manufacturers and countries invest a lot of resources in developing relative issues. Among the relative issues of the electric car, the battery and electric power management techniques may be the most important techniques.
The most significant capability of a high voltage battery management system is measuring the battery voltage, for avoiding the battery from overcharging or over-discharging. In order to measure the battery voltage precisely, the measurement circuit may include a microcontroller, an analog to digital converter, an operational amplifier, and a resistor for executing the measurement. However, the ageing and damaging problems, the ambient, and the work temperature may all influence the circuit characteristics of the electric components, and thus result in measurement errors.
Conventionally, the high voltage battery management system usually cannot determine the self-made measurement errors and do self calibration. The accuracy of voltage measurement which is done by the high voltage battery management system must be confirmed by external measurement devices, which causes extra costs and lowers usage convenience.